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Created by Jess Molyneux
about 9 years ago
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Question | Answer |
Name the 8 major tectonic plates. | Eurasian African Australian Pacific Indian Antarctic North American South American |
What causes the movement of tectonic plates? (Hint: where is this?) | Convection currents in the mantle beneath the crust |
Name the two different types of plate. | Continental Oceanic |
What type of rock are continental plates made up of? (Bonus: give some properties) | Granite Low density igneous rock 2.87g per cubic cm |
What type of rock are oceanic plates made up of? (Bonus: give some properties) | Basalt High density igneous rock 3.14g per cubic cm |
What name is given to plate margins where the plates are moving apart? | Constructive or divergent |
Give an example of a constructive plate margin. (Hint: where is it found? Which plates are involved? How long is it? How quickly is it forming?) | Mid Atlantic Ridge North American and Eurasian plates Moving apart at around 3cm per year 12 000 miles long Centre of Atlantic ocean |
What 3 changes would be observed at a constructive plate margin? | Plates move apart - fissures or rift valleys Magma rises to the surface - new crust Central mountains form |
What 3 hazards are associated with a constructive plate margin? | Fissure volcanoes OR volcanic islands Earthquakes along transform faults |
What are transform faults? (Bonus: why do earthquakes tend to occur along them? | Joins between different types or ages of bands of rock They are the weakest point so pressure builds there |
What name is given to plate margins where the plates are sliding past one another? | Conservative or transform |
Give an example of a conservative plate margin. (Hint: where is it found? Which plates are involved? What are the consequences?) | San Andreas Fault California Pacific and North American plates 5 large earthquakes from 1906 - 1994 |
What changes would be observed at a conservative plate margin? | No special surface features Sliding motion causes plates to stick or lock - pressure builds up - a sudden movement releases this tension and sends shockwaves |
What hazard is associated with a conservative plate margin? | Earthquakes |
What name is given to plate margins where the plates are moving towards one another? | Destructive or convergent |
What are the two types of destructive margin? (Bonus: distinguish between them) | Subduction zone (continental, oceanic OR oceanic, oceanic) Collision zone (continental, continental) |
Why does subduction occur when at least one of the plates is oceanic? | Oceanic plates are made up of basalt which is of a higher density (than granite) and so sinks |
Give an example of a subduction zone. (Hint: which plates are involved? What 3 changes have occurred?) | Nazca and South American plates Formed part of the Andes String of volcanoes along mountain crest Deep trench in Pacific ocean |
What 3 changes would be observed at a subduction zone? (Hint: consider both plates) | Continental plate forces oceanic into mantle (subduction) where it melts along with water and sea deposits Fold mountains are along edge of continental plate Oceanic trench formed |
What 2 hazards are associated with a subduction zone? (Bonus: and why?) | Earthquakes (intensive folding of the rock leads to slipping and breaking rock) Composite volcanoes (melted rock rises through continental plate - volcanic eruptions at surface, when the oceanic plate melts, gas is formed - explosive volcano) |
Why does subduction NOT occur between two continental plates? (Bonus: what does this mean for activity in these places?) | Both plates are too buoyant There is no volcanic activity - no new magma created |
Give two examples of collision zones. (Hint: which plates are involved? what changes have occurred?) | Eurasian and African plates - the Alps Indo-Australian and Eurasian - the Himalayas |
What change would be observed at a collision zone? | Pressure as plates move towards one another causes leading edge of both plates to buckle on collision - fold mountains created |
What hazard is associated with a collision zone? (Bonus: and why?) | Earthquakes (locking or sticking may occur and cause pressure to build) |
What characterises a fissure volcano? (Hint: there are 2 features) | Runny lava / lava fountains Long, flat vent |
Where are fissure volcanoes usually found or formed? | Constructive plate margins |
What characterises a composite volcano? (Hint: there are 3 features) | Thick, viscous lava Tall cone shape Explosive eruptions (due to pressure from sticky lava) |
Where are composite volcanoes usually found or formed? | Subduction zones |
What characterises a shield volcano? (Hint: there are 2 features) | Low cone, gentle slope Runny lava |
What are hotspots? | Small areas of the Earth's crust where unusually high heat flow is associated with volcanic activity |
Explain the presence of extinct volcanoes close to hotspots. | A plume of heat directly from the core created the volcano. Plate movement caused it to move off the hotspot so no longer had a supply of magma. |
Give an example of a hotspot which has created a string of volcanic islands. (Bonus: how long is it?) | Hawaii String of volcanic islands 3,700 miles long |
What may cause an earthquake in an area distant from a plate boundary? (Hint: there are 3 things) | Fault lines Rising land (previously crushed by glaciers) Historic plate collision - lines of weakness |
Why is the San Andreas Fault particularly prone to earthquakes? | Not a single fracture Line of interrelated faults 'Domino effect' when tension released |
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